American Welding Society D17.1 “Specification for Fusion Welding for Aerospace Applications” is the industry standard for becoming a certified welder for fabricating or repairing aircraft parts.
Back in the day, MIL std 5021 was the standard and cluster welds of tubing spliced to plate where the standard test given to certify welders.
Then MIL std 1595a came along and addressed different metal types and newer processes like electron beam and laser. Mil std 1595a was later renamed AMS 1595a with no changes in the document other than name.
AWS D17.1 is the latest and greatest specification for certifying welders and serves not only as a standard for certifying welders, but also a specification for all welding processes used in the aviation and aerospace industries.
Basically here is how the welding certification part works:
Metals are categorized into 8 categories or groups. (1. carbon low alloy, 2. iron based stainless steels, 3. nickel alloys, 4. aluminum, 5. magnesium, 6. titanium, 7. cobalt alloys, 8. refractory alloys like columbium, tantalum etc.)
metal groups 1,2,and 3 are further separated into a and b categories with the b category considered the most difficult to weld.
Groove welds and fillet welds are used to certify welders. Usually a test joint in the.032″ -.050″ thickness range is used for the welding certification tests but AWS D17.1 has provisions for all thicknesses of metals.
Usually 2 inch by 5 inch plates are used for the groove weld tests in this thickness.
Groove welds are often x rayed, but bend testing is sometimes used
Fillet welds (tee joints) are required in order for the welder to be qualified to weld a fillet weld below.063″
Groove welds qualify for fillet welds too for everything over.063″
Tips for passing an aerospace welding certification test:
- Make sure your vision is good. ( AWS D17.1 even requires a vision test)
- Use extra magnification for the thin stuff. Even with good vision, seeing a puddle on inconel 718 that is.032″ thick can be difficult. If you cant see it, you cant weld it.
- Keep your tungsten electrodes sharp and clean
- Keep as close an arc and you dare without dipping your wick.
- If you dip your wick, stop and change electrodes.
- Clean the metal and file the sheared edge of any groove weld, especially aluminum, magnesium, and titanium.
- Follow the WPS if one is provided. Sometimes the test inspector looks for your ability to follow technical instructions as well as your ability to pass a welding test.